1. Field of the Invention
The present invention relates to a vertical engine in which a chain circulated in a generally horizontal plane is wound around sprockets mounted on first and second shafts each disposed in a generally horizontal direction.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 9-41909 discloses a vertical engine in which a timing chain for transmitting a driving force from a crankshaft to a camshaft is accommodated within a chain cover covering upper surfaces of a cylinder block and a cylinder head of the engine.
Japanese Patent Application Laid-open No. 2001-98951 discloses a vertical engine for an outboard engine system in which a timing chain for transmitting a driving force from a crankshaft to a camshaft is disposed between lower surfaces of a cylinder block and a cylinder head of the engine and an upper surface of an engine holder supporting the engine.
In general, in a vertical engine including a timing chain disposed in a horizontal plane, the plane of disposition of the timing chain is perpendicular to a direction in which an oil returned to an oil pan is dropped by gravitation. For this reason, frequency of contact of the oil with the timing chain is decreased, so that it is difficult to lubricate the timing chain.
Especially, in the vertical engine described in Japanese Patent Application Laid-open No. 9-41909, the timing chain is disposed at an upper portion of the engine, however, it is not that a special lubricating device for the timing chain is mounted, and rather only an amount of the oil as much as comparable to mist is supplied to a breather chamber. Thus, there is a fear that the lubrication of the timing chain is insufficient, resulting in a reduction in durability. On the other hand, in the vertical engine described in Japanese Patent Application Laid-open No. 2001-98951, the timing chain is disposed at a lower portion of the engine and hence, the timing chain can be lubricated by the oil which has lubricated various portions of the engine and dropped into the oil pan. However, the oil cannot be entrained on the timing chain disposed in the horizontal plane as described above, and it is difficult to bring the oil into sufficient contact with the timing chain.